The present invention is a method of preparing an alkoxysilane having reduced halide content. The method comprises contacting a mixture comprising an alkoxysilane and residual halide with a mixture comprising about 1.5 to 15 moles of an alkyl alcohol per mole of residual halide, the alkyl alcohol comprising 1 to about 4 carbon atoms and about 0.1 to 5 moles of an orthoformate per mole of residual halide, to form a mixture comprising additional alkoxysilane and lower boiling species, and separating the lower boiling species and the alkoxysilane. Remaining residual halide may be contacted alkali with metal to further reduce the halide content. Alkoxysilanes are useful as catalyst modifiers to manufacture polypropylene.
Shorr, U.S. Pat. No. 2,698,861, describes a method of preparing alkoxysilicon compounds comprising reacting a halosilicon compound selected from the group consisting of halosilanes and partial hydrolyzates with an orthoformate. The by-products of the reaction are an alkyl halide, residual halide species, and a formic acid ester.
Ashby, U.S. Pat. No. 4,281,146, describes a method of neutralizing a halogen silicone compound comprising adding to the halogen silicone compound an orthoformate and an alcohol to form an alkyl chloride and a formate which can then be distilled off. The method uses excess trimethylorthoformate to neutralize the halogen silicone compound which is expensive and undesirable on a commercial scale.
The present invention provides a method for reducing the halide content of alkoxysilanes. In addition, a method is provided to reduce the residual halide content of alkoxysilanes while reducing alkali metal salt formation and filtration cycle time. Furthermore, the invention provides a method for reducing the halide content of sterically hindered alkoxysilanes.